fs/bcachefs/seqmutex.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _BCACHEFS_SEQMUTEX_H
   3 #define _BCACHEFS_SEQMUTEX_H
   4
   5 #include <linux/mutex.h>
   6
   7 struct seqmutex {
   8         struct mutex    lock;
   9         u32             seq;
  10 };
  11
  12 #define seqmutex_init(_lock)    mutex_init(&(_lock)->lock)
  13
  14 static inline bool seqmutex_trylock(struct seqmutex *lock)
  15 {
  16         return mutex_trylock(&lock->lock);
  17 }
  18
  19 static inline void seqmutex_lock(struct seqmutex *lock)
  20 {
  21         mutex_lock(&lock->lock);
  22         lock->seq++;
  23 }
  24
  25 static inline u32 seqmutex_unlock(struct seqmutex *lock)
  26 {
  27         u32 seq = lock->seq;
  28         mutex_unlock(&lock->lock);
  29         return seq;
  30 }
  31
  32 static inline bool seqmutex_relock(struct seqmutex *lock, u32 seq)
  33 {
  34         if (lock->seq != seq || !mutex_trylock(&lock->lock))
  35                 return false;
  36
  37         if (lock->seq != seq) {
  38                 mutex_unlock(&lock->lock);
  39                 return false;
  40         }
  41
  42         return true;
  43 }
  44
  45 #endif /* _BCACHEFS_SEQMUTEX_H */